The present invention relates to novel compositions curable thermally and with actinic radiation (dual-cure compositions). The present invention also relates to the use of the novel dual-cure compositions as adhesives and sealing compounds and as coating materials in automotive OEM finishing, automotive refinish, furniture coating, and industrial coating, including coil coating, container coating and the coating of electrical components. The present invention additionally relates to novel processes for preparing dual-cure compositions. The present invention further relates to novel processes for producing adhesive films, seals and single-coat or multicoat clearcoat systems or color and/or effect paint systems on primed and unprimed substrates using dual-cure compositions. The present invention relates not least to primed and unprimed substrates which feature the novel adhesive films, seals and/or single-coat or multicoat clearcoat systems or color and/or effect paint systems.
Coatings, especially single-coat or multicoat clearcoat systems or color and/or effect paint systems, seals and adhesive films which are three-dimensionally crosslinked by way of urethane groups have numerous advantages which include a comparatively high weathering stability, chemical resistance and mar resistance. Manufacturers and users are therefore equally endeavored to provide coating materials, adhesives and sealing compounds whose constituents are easy to prepare and which provide polyurethane coatings, adhesive films and seals with an ever further improved and optimized profile of properties.
In this context, coating materials, adhesives and sealing compounds which are curable both thermally and with actinic radiation (dual-cure coating materials, adhesives and sealing compounds) are increasingly gaining in interest, since they offer numerous advantages.
Firstly, for instance, dual-cure coating materials are more suited to the coating of heat-sensitive substrates than are coating materials curable only by means of heat, since in the dual-cure systems any incomplete thermal curing at low temperatures may be compensated by curing with actinic radiation, resulting overall in coatings having good performance properties. Secondly, dual-cure coating materials are more suited to the coating of three-dimensional substrates of complex shape than are coating materials curable with actinic radiation only, since incomplete radiation curing in the shadow regions of the substrates may be compensated by thermal curing, resulting overall, here again, in coatings having good performance properties.
The same applies mutatis mutandis, to the dual-cure adhesives and sealing compounds as well.
Dual-cure coating materials providing coatings containing urethane groups in their three-dimensional network are known.
For instance, European patent EP-A-0 549 116 describes a dual-cure coating material which comprises a constituent containing free isocyanate groups and photopolymerizable, olefinically unsaturated double bonds, a reactive diluent and also, where appropriate, a photoinitiator. Films of this known dual-cure coating material are cured initially with actinic radiation, especially UV light. Thereafter, the resulting coatings are subjected to a moisture cure, as a result of which the three-dimensional network is consolidated by the formation of urethane group and urea groups from the free isocyanate groups. A disadvantage is that the crosslinking partners contemplated comprise only water and no other isocyanate-reactive constituents, crosslinkers or binders containing isocyanate-reactive groups, for example. Accordingly, a very important possibility of broadly varying the profile of properties of the dual-cure coating materials and of the coatings produced from them is absent. Moreover, the result of the water cure is highly dependent on the atmospheric humidity employed, the temperature, the network density, and other parameters, and so is difficult to reproduce.
The European patent application EP-A-0 928 800, on the other hand, discloses a dual-cure coating material which comprises a urethane (meth)acrylate containing free isocyanate groups and (meth)acryloyl groups, a photoinitiator and an isocyanate-reactive compound, particularly a polyol or polyamine. This dual-cure coating material does afford the possibility of varying the profiles of properties of coating material and of coating and of adapting them in a targeted way to different end uses.
The disadvantage of both known dual-cure coating materials is that they comprise what are known as two-component systems, in which the constituents containing free isocyanate groups have to be stored separately from the constituents containing the isocyanate-reactive groups and/or in the absence of water, up until the time of application, in order to avoid premature crosslinking. To accomplish this, however, necessitates a relatively high level of technical and planning effort in terms of storage, production and application.
The same applies, mutatis mutandis, to the corresponding dual-cure adhesives and sealing compounds as well.
This effort is not required, admittedly, with the coating materials known from U.S. Pat. Nos. 5,474,811, 5,356,669, 5,605,965, WO 94/10211, WO 94/10212, WO 94/10213, EP-A-0 594 068, EP-A-0 594 071 or EP-A-0 594 142. These coating materials comprise at least one oligomer and/or polymer containing at least one pendant and/or terminal carbamate group of the formula:
xe2x80x94Oxe2x80x94(CO)xe2x80x94NH2
and at least one crosslinking agent containing at least two carbamate-reactive groups. These known coating compositions therefore constitute one-component systems and provide clearcoats which exhibit extremely high mar resistance and etch resistance. However, they cannot be cured additionally using actinic radiation. The same applies to the corresponding dual-cure adhesives and sealing compounds.
It is an object of the present invention to provide novel dual-cure compositions which no longer have the disadvantages of the prior art and which provide coatings, adhesive films and seals which contain urethane groups and have excellent performance properties. In particular, the novel dual-cure compositions ought to constitute one-component systems, in which binder and crosslinking agent are present alongside one another without prematurely crosslinking.
Following application, they ought to crosslink rapidly under the influence of heat and actinic radiation, at comparatively low temperatures, so that they are also suitable for the coating, bonding and sealing of thermally sensitive substrates. The resulting novel coatings, adhesive films and seals ought to exhibit excellent weathering stability, chemical resistance, hardness, flexibility and mar resistance, so that they are highly suitable in particular for automotive OEM finishing, automotive refinishing, furniture coating and industrial coating, including coil coating, container coating and the coating of electrical components, and also the bonding and sealing of the substrates used in these applications.
Found accordingly have been the novel compositions curable thermally and with actinic radiation (dual-cure compositions) which comprise
A) at least one constituent containing on average per molecule at least one primary or secondary carbamate group and at least one bond which can be activated with actinic radiation, which constituent is preparable by
1. in accordance with a first variant
1.1 in a first process step, reacting at least one polyfunctional compound containing at least two isocyanate-reactive, acid-reactive or epoxide-reactive functional groups with in each case at least one compound containing an isocyanate group, acid group or epoxide groups and also at least one bond which can be activated with actinic radiation, and subsequently, in a second process step, reacting the resultant intermediate, which on average still contains at least one free isocyanate-reactive, acid-reactive or epoxide-reactive functional group, with in each case at least one compound by means of which carbamate groups are introduced; or
1.2 in a first process step, reacting at least one polyfunctional compound containing at least two isocyanate-reactive, acid-reactive or epoxide-reactive functional groups with in each case at least one compound by means of which carbamate groups. are introduced, and subsequently, in a second process step, reacting the resultant intermediate, which on average still contains at least one free isocyanate-reactive, acid-reactive or epoxide-reactive functional group, with in each case at least one compound containing an isocyanate group, acid group or epoxide groups and also at least one bond which can be activated with actinic radiation;
2. in accordance with a second variant
2.1 in a first process step, reacting at least one polyisocyanate, polyacid or polyepoxide with in each case at least one compound containing at least one bond which can be activated with actinic radiation and also one and also one isocyanate-reactive, acid-reactive or epoxide-reactive functional group, and subsequently reacting the resultant intermediate, which on average still contains at least one isocyanate group, acid group or epoxide group, in a second process step with in each case at least one compound containing at least one carbamate group or at least one functional groups which can be converted into carbamate groups, and also containing an isocyanate-reactive, acid-reactive or epoxide-reactive functional group; or
2.2 in a first process step, reacting at least one polyisocyanate, polycarboxylic acid or polyepoxide with in each case at least one compound containing at least one carbamate group or at least one functional groups which can converted into carbamate groups, and also an isocyanate-reactive, acid-reactive or epoxide-reactive functional group, and subsequently reacting the resultant intermediate, which on average still contains at least one isocyanate group, acid group or epoxide group, in a second process step with in each case at least one compound containing at least one bond which can be activated with actinic radiation and also one isocyanate-reactive, acid-reactive or epoxide-reactive functional group; or
3. in accordance with a third variant, reacting at least one polyisocyanate, polyacid or polyepoxide in a one-pot process with at least one compound containing at least one carbamate group or at least one functional groups which can be converted into carbamate groups, and also one isocyanate-reactive, acid-reactive or epoxide-reactive functional group, and at least one compound containing at least one bond which can be activated with actinic radiation and also one isocyanate-reactive, acid-reactive or epoxide-reactive functional group; and
B) at least one constituent containing on average per molecule at least one carbamate-reactive functional group and also, if desired, at least one bond which can be activated with actinic radiation.